I'm not so sure that we can deduce anything much about the depth. The shoreline gradient is very small, yet even for the (one would think) shallows near the shore no bottom reflection is detected, presumably because the direct reflection from the surface is just so much brighter. I note that "T60 will provide another . . opportunity where the observation can be tuned better" - maybe to look specifically for a bottom echo?? And before that there is the T58 SAR. How much will it resemble the northern lakes?

Exciting stuff.

Oh - I almost forgot there's a few other abstracts to look at as well !!!

Taking this together with earlier VIMS results, may we tentatively conclude that the ISS- and SAR- areas hitherto coloured blue on published images actually comprise significant areas of gently sloping 'mudflat' as well as areas of standing liquid? If so we have to question how much of the large northern lake district is actually liquid-covered. Are the SAR details seen inside the inferred shorelines mudlats, lake bed features, or a mixture of the two? Will it require altimetry to find out? What are the implications for the proposed lake boat?

But apparently not perceived as such by the program committee - I got postered.Apparently the tired old story of salts on Europa and some other reruns were considered more worthy of oral presentation... :-{

Or perhaps other 'disadvantaged' topics were felt to be in need of positive discrimination?

Anyhow, for us distant abstract-consumers one format is much like another and each new revelation is a treasure.

Perhaps Ralph will take a question from the floor here. It's about surface gravity waves on the lake. I would like to ask whether this observation, or others like it, can be used to place limits on either the height or gradient of surface waves. For example can we say from this that the surface (in the brightest part) is smooth and flat right down to centimetre scales?

But apparently not perceived as such by the program committee - I got postered.Apparently the tired old story of salts on Europa and some other reruns were considered more worthy of oral presentation... :-{

Perhaps Ralph will take a question from the floor here. It's about surface gravity waves on the lake. I would like to ask whether this observation, or others like it, can be used to place limits on either the height or gradient of surface waves. For example can we say from this that the surface (in the brightest part) is smooth and flat right down to centimetre scales?Or is there still the possibility of an oily swell? (sorry)

Yes, the echo shape and amplitude (and the radiometry) pose severe constraints on how flat the lakesurface must be - a detailed modeling effort is ongoing.

A huge thank you (again) for making another fascinating paper available to all. I haven't had time to digest it fully, but noticing this concluding sentence

Knowledge of the amplitude of the changes will require reliable topographicinformation over Ontario Lacus with both high precisionand fine spatial resolution — the T49 RADAR altimetry pass, shouldit occur, will shed light on these processes.

reminded me that we already have a link to that altimetry profile in post 15 of this thread.

Is anybody going to have a go at matching the altimetry to the VIMS map of the lake's southeastern margin? Did the altimeter track pass over those red islands in the VIMS interpretation diagram?

A nice feature of the VIMS is the clear boundary between unit 1, interpreted as standing liquid, and unit 2, interpreted as possible mudflat. The distinction seems to be less marked in radar SAR images of the northern lakes, presumably because the liquid is just too transparent to microwaves and it's surface virtually invisible (unless you're looking straight down in altimetry mode at the specular reflection of the transmitter).

Is anybody going to have a go at matching the altimetry to the VIMS map of the lake's southeastern margin? Did the altimeter track pass over those red islands in the VIMS interpretation diagram?

A nice feature of the VIMS is the clear boundary between unit 1, interpreted as standing liquid, and unit 2, interpreted as possible mudflat. The distinction seems to be less marked in radar SAR images of the northern lakes, presumably because the liquid is just too transparent to microwaves and it's surface virtually invisible (unless you're looking straight down in altimetry mode at the specular reflection of the transmitter).

I saw a profile across it somewhere -- which probably means that Ralph showed it to me. So hopefully he'll put an explicit comparison in an upcoming Ontario Lacus altimetry paper.

As an amateur who is fascinated by Titan - and in particular its lakes and 'methano-ethanological' cycle - I thought that this 19Aug abstract was v interesting. While not proof that Ontario Lacus is filled with liquid, I think that there would be few people who would bet a week's wages on it having any sort of solid surface after reading about how incredibly smooth it is.

It is interesting to see how this research has been built on data from the T49 Dec08 pass. I read a paper a while ago by Ralph (Lorenz - who posts regularly right here) on this pass. Very interesting regarding the specular reflection. http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1990.pdf ....Now team member Lauren Wye (whose speciality is signal detection) has built on this, by working out a way to more accurately analyze the strength of the specular return by partly overcoming distortion factors caused by the flash. This has allowed an upper boundary in height variation of the surface to be set at 3mm.

To me this looks like a brilliant conclusion to the work of a highly multiskilled team! Congratulations. (No pun intended - it is more than a flash in the pan!).

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted.
Do not reproduce without permission. Read
here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the
individual posters and do not necessarily reflect the opinions
of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer
UnmannedSpaceflight.com moderation team is wholly independent
of The Planetary Society. The Planetary Society has no influence
over decisions made by the UnmannedSpaceflight.com moderators.

SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society
and is funded by donations from visitors and members. Help keep
this forum up and running by contributing
here.